Route 99: 10
counties.Route 99 is what is left of US 99, running from
I-5 N of Los Angeles, through Bakersfield, Fresno, and Sacramento, to rejoin
I-5 in northern California. Counties traversed: Kern, Tulare, Fresno, Madera,
Mariposa, Stanislaus, San Joaquin, Sacramento, Sutter, and Butte. #5 in total
length.

I-80: 10 counties.I-80 runs to the Nevada border from San Francisco, through
Sacramento. Counties traversed: San Francisco, Alameda, Contra Costa, Napa,
Solano, Yolo, Sacramento, Placer, Nevada, and Sierra. Not in the top 10 for
total length.

3.

Route 1: 12 counties.Route 1 runs from southern Orange County to US 101 near Leggett,
hugging the coast most of the way. Counties traversed: Orange, Los Angeles,
Ventura, Santa Barbara, San Luis Obispo, Monterey, Santa Cruz, San Mateo, San
Francisco, Marin, Sonoma, and Mendocino. #3 in total length.

Route 33: 9 counties.Route 33 runs from Ventura in various segments up to I-5 near
Vernalis. Counties traversed: Ventura, Santa Barbara, San Luis Obispo, Kern,
Kings, Fresno, Merced, Stanislaus, and San Joaquin.. #10 in total length.

5.

Route 89: 10 counties.Route 89 runs from US 395 near Coleville to I-5 near Mt. Shasta.
Counties traversed: Mono, Alpine, El Dorado, Placer, Nevada, Sierra, Plumas,
Tehama, Shasta, and Siskiyou. Not in the top 10 for total
length.

7.

US 395: 7
counties.US 395 currently runs from north of San
Bernardino to the Oregon border, with a break when it passes through Nevada.
Counties traversed: San Bernardino, Kern, Inyo, Mono, Sierra, Lassen, and
Modoc. #4 in total length.